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Blue-Green Algae: A Lurking Danger for Pets

July 15, 2021

Have you ever heard of cyanobacteria? You may know it as blue-green algae. This is an extremely dangerous type of algae, one that typically lives in warm, nutrient-rich water. Cyanobacteria can make both people and pets really sick. In certain conditions, it can grow very rapidly, or bloom. Unfortunately, these blooms are becoming much more common. A local veterinarian discusses cyanobacteria below.

 Warning Signs

Blue-green algae blooms will usually occur in summer and early fall, but they can happen anytime the water temperature stays over 75°F for long periods. Many local authorities and newscasts will alert people when a body of water has been contaminated by cyanobacteria.  Some will post signs and/or close swimming holes. However, it can be easy to miss these updates. The EPA has a map online here with cyanobacteria resources for every state. This is definitely something you want to check before taking Fido swimming, especially if you’re in a spot you’ve never been to before.


Cyanobacteria typically looks like pea soup or green paint. It can also cause a swampy odor. However, you can’t judge a body of water by appearance alone. Smaller blooms can still be dangerous, but they may not visibly alter the look (or smell) of a lake or pond very much. It’s also worth noting that, while not all algae blooms are as harmful as blue-green ones, you can’t tell by looking at a lake whether it is or isn’t safe. Err on the side of caution here: if in doubt, just stay out! 


As mentioned above, blue-green algae is extremely toxic. You don’t necessarily have to drink contaminated water to get sick: you can also ingest or absorb it through skin contact or by breathing in water droplets or vapors. This can happen when you are swimming, boating, or tubing. Cyanobacteria can also stick to pets’ fur, where they can later lick it off.


Blue-green algae can make any animal sick, and is very dangerous to wildlife. Dogs are particularly at risk, especially those that love to swim and/or play in water. Blue-green algae can cause very serious health issues, including neurological problems and liver failure. Unfortunately, it can be fatal. Warning signs include panting, respiratory problems, vomiting, diarrhea, dizziness/disorientation, seizures, and excessive drooling. If your pup shows any of these warning signs, call your vet or an emergency clinic immediately.


As always, prevention is worth much more than cure. Be very careful when choosing Fido’s swimming holes, and don’t let your furry buddy drink from lakes or ponds, especially ones with blue-green scum. 

Do you have questions about pet care? Contact us, your animal clinic, today!